LP2986ILD-3.3 Datasheet, PDF (15/26 Pages) Texas Instruments – Micropower, 200 mA Ultra Low-Dropout Fixed or Adjustable Voltage Regulator

LP2986
www.ti.com
SNVS137H – MARCH 1999 – REVISED APRIL 2013
REVERSE INPUT-OUTPUT VOLTAGE
The PNP power transistor used as the pass element in the LP2986 has an inherent diode connected between
the regulator output and input.
During normal operation (where the input voltage is higher than the output) this diode is reverse-biased.
However, if the output voltage is pulled above the input, or the input voltage is pulled below the output, this diode
will turn ON and current will flow into the regulator output pin.
LP2986
V_IN
PNP
V_OUT
GND
In such cases, a parasitic SCR can latch which will allow a high current to flow into V_IN (and out the ground pin),
which can damage the part.
In any application where the output voltage may be higher than the input, an external Schottky diode must be
connected from V_IN to V_OUT (cathode on V_IN, anode on V_OUT), to limit the reverse voltage across the LP2986 to
0.3V (see the Absolute Maximum Ratings section.
SCHOTTKY DIODE
LP2986
V_IN
PNP
V_OUT
GND
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